This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. We propose to measure physiologic and psychological parameters before, during, and following standardized treadmill walking tests in young adult obese men and women who are fed diets containing diffrent amounts and types of carbohydrate and different amounts of fat and protein. The main outcomes of this study are serum concentrations of metabolic fuels, glucose and fatty acids, during standarized exercise testing, as well as participants'psychological responses during and following standardized exercise testing. Secondary outcomes will focus on free-living psychological profiles of mood, perceived energy level, and feelings about exercise over the course of each weekly treatment period.